#include <stdio.h>
#include <string.h>
#define TOUPPER(c) ('a'<=(c)&(c)<='z'?(c)-'a'+'A':(c))
int main(void)
{
    char s[10];
    int i;
    strcpy(s, "abcd");
    puts(s);
    i = 0;
    putchar(TOUPPER(s[++i]));
    putchar('\n');

    strcpy(s, "0123");
    i = 0;
    putchar(TOUPPER(s[++i]));
    putchar('\n');
    return 0;
}